Sixty-three of 435 (14.5%) samples collected from broiler chickens were positive for C. jejuni. Twenty-two of 55 samples were from organic chickens (40%) and 41 of 380 samples were from conventional chickens (10.8%). Isolates were subjected to macrorestriction profiling using SmaI and analyzed for their ability to survive in macrophage cells and invade in epithelial cells. Antibiotic testing to cefaclor, ciprofloxacin, tetracycline, erythromycin, gentamicin, trimethroprim/sulfamethoxazole, and ampicillin were performed. Finally, 5 isolates of varying putative in vitro virulence traits were chosen for experimental inoculation of newborn piglets. Five piglets per isolate were tested and examined macroscopically and microscopically upon necropsy. Genotyping of isolates indicated 1 to 3 profiles per flock. Of the 22 organic isolates from chickens, only 3 (13.6%) were able to survive within macrophages. For the conventional isolates, 21 out of 41 (51.2%) were able to survive. However, the majority of isolates (90.5%) from both organic and conventional isolates were not capable of invading epithelial cells. No isolates exhibited resistance to ciprofloxacin or gentamicin. One isolate out of 63 (1.6%) was resistant to erythromycin, 52 (82.5%) to tetracycline, 28 (44.4%) to trimethroprim/sulfamethoxazole, and 6 (9.5%) to cefaclor. In terms of the piglet studies, regardless of the combination of in vitro invasion or survival results or type of flock, most piglets (16/25) in all groups exhibited hyperemia, edema, and hemorrhage in the small intestine or colon upon gross examination. Microscopic examination revealed congested mucosa and erosion of the epithelium in 10 of the 25 piglets from 4 of the 5 groups. In conclusion, this study suggests that C. jejuni isolated from broiler chickens are virulent in piglets and are probably capable of causing disease in humans. Furthermore, the results of the survival and invasion assays did not correlate with the results of the piglet studies and cannot be relied upon to predict degree of virulence. Therefore, another virulence factor is responsible for the pathogenesis, such as a toxin(s). As this is the first study to confirm putative in vitro virulence traits with an animal model, further research is recommended with the piglet model to assess pathogenicity.

Sixty-three of 435 (14.5%) samples collected from broiler chickens were positive for C. jejuni. Twenty-two of 55 samples were from organic chickens (40%) and 41 of 380 samples were from conventional chickens (10.8%). Isolates were subjected to macrorestriction profiling using SmaI and analyzed for their ability to survive in macrophage cells and invade in epithelial cells. Antibiotic testing to cefaclor, ciprofloxacin, tetracycline, erythromycin, gentamicin, trimethroprim/sulfamethoxazole, and ampicillin were performed. Finally, 5 isolates of varying putative in vitro virulence traits were chosen for experimental inoculation of newborn piglets. Five piglets per isolate were tested and examined macroscopically and microscopically upon necropsy. Genotyping of isolates indicated 1 to 3 profiles per flock. Of the 22 organic isolates from chickens, only 3 (13.6%) were able to survive within macrophages. For the conventional isolates, 21 out of 41 (51.2%) were able to survive. However, the majority of isolates (90.5%) from both organic and conventional isolates were not capable of invading epithelial cells. No isolates exhibited resistance to ciprofloxacin or gentamicin. One isolate out of 63 (1.6%) was resistant to erythromycin, 52 (82.5%) to tetracycline, 28 (44.4%) to trimethroprim/sulfamethoxazole, and 6 (9.5%) to cefaclor. In terms of the piglet studies, regardless of the combination of in vitro invasion or survival results or type of flock, most piglets (16/25) in all groups exhibited hyperemia, edema, and hemorrhage in the small intestine or colon upon gross examination. Microscopic examination revealed congested mucosa and erosion of the epithelium in 10 of the 25 piglets from 4 of the 5 groups. In conclusion, this study suggests that C. jejuni isolated from broiler chickens are virulent in piglets and are probably capable of causing disease in humans. Furthermore, the results of the survival and invasion assays did not correlate with the results of the piglet studies and cannot be relied upon to predict degree of virulence. Therefore, another virulence factor is responsible for the pathogenesis, such as a toxin(s). As this is the first study to confirm putative in vitro virulence traits with an animal model, further research is recommended with the piglet model to assess pathogenicity.

en_US

dc.type

text

en_US

dc.type

Dissertation-Reproduction (electronic)

en_US

dc.subject

Biology, Microbiology.

en_US

dc.subject

Environmental Sciences.

en_US

thesis.degree.name

Ph.D.

en_US

thesis.degree.level

doctoral

en_US

thesis.degree.discipline

Graduate College

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thesis.degree.discipline

Soil, Water and Environmental Science

en_US

thesis.degree.grantor

University of Arizona

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dc.contributor.advisor

Gerba, Charles P.

en_US

dc.contributor.advisor

Joens, Lynn A.

en_US

dc.identifier.proquest

3177541

en_US

dc.identifier.bibrecord

.b49001127

en_US

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